S2 idling too high
Discussion
Hello, Nick has been struggling to get his TVR to idle correctly. He used a Gunson Fault Code Reader to put the car into code 60, and then timed it to 8degrees BTDC. This led to an idle of 2000rpm. He was then informed the correct timing may be between 12 and 15 BTDC, so he then changed the car to this, but this, if anything, increased the revs. The car also begins to idle normally at around 1k, but after a second or so decided to rise to 2k. If the Idle Speed Control Valve is disconnected, it idles reasonably normally (si the ISCV actually necessary or can it be ditched?).
After a lengthy phone call to Norman, he has been trawling through old threads, and reading an article about timing the 2.9 V6. Here is where he's at so far:
1. Throttle butterflys are closing fully
2. Idle speed control valve has been cleaned, new gasket applied. It is working correctly.
3. The brake servo is NOT the issue, the pipe has been disconnected and he has placed his thumb over the hole in the plenum; no change (if anything the revs DROPPED when the hole was open).
4. The throttle potentiometer may be damaged; he used a multimeter on it; two of the pins gave normal readings, but the third gave an erratic reading, going up and down; could this cause a high idle?
Through reading whats been posted in previous threads and in the article in car mechanic that Norman emailed, he has drawn up a plan of action:
1. Warm engine up, let it cool, see if this resets ecu.
2. Check water temperature sensor.
3. Check crank case return valve.
4. Re adjust throttle stop screw. Where should it be? (his tutor fiddled with it).
5. Pass a butance/propane torch over the engine to see if the revs rise, indicating an air leak.
Does the octane service socket need to be cut off to achieve code 60? If so, do you literally slice it off or is there a better way? If so, where is this octane socket?
If the throttle pot switch (is this the throttle potentiometer or is it different?) is removed, can the engine be timed without having to use the Gunson Fault Code Reader (these seem VERY unreliable and a bit hit and miss according to Nick).
Thanks,
Tony
After a lengthy phone call to Norman, he has been trawling through old threads, and reading an article about timing the 2.9 V6. Here is where he's at so far:
1. Throttle butterflys are closing fully
2. Idle speed control valve has been cleaned, new gasket applied. It is working correctly.
3. The brake servo is NOT the issue, the pipe has been disconnected and he has placed his thumb over the hole in the plenum; no change (if anything the revs DROPPED when the hole was open).
4. The throttle potentiometer may be damaged; he used a multimeter on it; two of the pins gave normal readings, but the third gave an erratic reading, going up and down; could this cause a high idle?
Through reading whats been posted in previous threads and in the article in car mechanic that Norman emailed, he has drawn up a plan of action:
1. Warm engine up, let it cool, see if this resets ecu.
2. Check water temperature sensor.
3. Check crank case return valve.
4. Re adjust throttle stop screw. Where should it be? (his tutor fiddled with it).
5. Pass a butance/propane torch over the engine to see if the revs rise, indicating an air leak.
Does the octane service socket need to be cut off to achieve code 60? If so, do you literally slice it off or is there a better way? If so, where is this octane socket?
If the throttle pot switch (is this the throttle potentiometer or is it different?) is removed, can the engine be timed without having to use the Gunson Fault Code Reader (these seem VERY unreliable and a bit hit and miss according to Nick).
Thanks,
Tony
King Fisher said:
4. The throttle potentiometer may be damaged; he used a multimeter on it; two of the pins gave normal readings, but the third gave an erratic reading, going up and down; could this cause a high idle?
I think you need to be sure that the TP is good before doing much else.I had a problem with my S3 years ago when it started randomly idling at high speeds - anything up to about 2k and after much messing about (TP resistance etc readings seemed to be OK) the TP was replaced and problem sorted. Apparently even if the resistance reading seems OK there can be issues which can cause some sort of a spike so maybe your TP needs replacing - worth trying that I suspect.
Jim
Jim
jimed said:
I had a problem with my S3 years ago when it started randomly idling at high speeds - anything up to about 2k and after much messing about (TP resistance etc readings seemed to be OK) the TP was replaced and problem sorted. Apparently even if the resistance reading seems OK there can be issues which can cause some sort of a spike so maybe your TP needs replacing - worth trying that I suspect.
Jim
If you are changing the TP dont forget the replacement types with GOLD connectors need the wiring modified if your existing one has SILVER connectorsJim
What about the electrical connectors from the sensors mentioned? I removed a bunch of mine in a part of the harness as it passes near the coil. The reason I removed them and replaced with soldered joints is that the cables pulled out of the old crimps easily indicating high resistance joints.
The car did run better afterwards.
The car did run better afterwards.
He'd put the bloody idle speed control valve on the wrong way round!!!!!!! now idling at a steady 900rpm.
In other news, he drove it round the college campus today (private land before anyone asks), and the car decided to cut out on him completely, as it did before he rebuilt it. The fuel pump is not priming. Fuel pump relay?
Also, it seems hesistant on power; he wound the air flow meters in, then wound them back by 1.5 turns, which is apparently the base setting for these engines. What may be causing the hesitation? (basically its slower than before!!).
In other news, he drove it round the college campus today (private land before anyone asks), and the car decided to cut out on him completely, as it did before he rebuilt it. The fuel pump is not priming. Fuel pump relay?
Also, it seems hesistant on power; he wound the air flow meters in, then wound them back by 1.5 turns, which is apparently the base setting for these engines. What may be causing the hesitation? (basically its slower than before!!).
If its still at the college go and sweet talk around the science department - get them to bring an oscilloscope along with someone that knows how to work it and get them to look at the voltage output from the throttle pot.
It needs to be nice and steady like this (and increasing as you open the throttle - not decreasing).
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
If it flickers or suddenly jumps at all your throttle pot is pooped.
This is on a V8 but its exactly the same principle.
Edited to add - it has been through a full warm up / cool down cycle at least once? - I understand this is critical to the engine discovering the range coming out of the various sensors.
It needs to be nice and steady like this (and increasing as you open the throttle - not decreasing).
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
If it flickers or suddenly jumps at all your throttle pot is pooped.
This is on a V8 but its exactly the same principle.
Edited to add - it has been through a full warm up / cool down cycle at least once? - I understand this is critical to the engine discovering the range coming out of the various sensors.
Throttle Pot Switch, TPS, Throttle Potentiometer are all the same.
I would say NO to ditching the ISCV
Timing should be 12 degrees at 975 rpm
Who told you to slice the octane scket ??? You don't want to do that. Leave it alone.
Like others I suspect the TPS and would double check the ISCV and check for airleaks in your AFM to plenum hoses as well as the plenum itself as you have said previously you have a wrong bolt in one hole.
K
I would say NO to ditching the ISCV
Timing should be 12 degrees at 975 rpm
Who told you to slice the octane scket ??? You don't want to do that. Leave it alone.
Like others I suspect the TPS and would double check the ISCV and check for airleaks in your AFM to plenum hoses as well as the plenum itself as you have said previously you have a wrong bolt in one hole.
K
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